This invention relates to an improved membrane keyboard and particularly a compact membrane keyboard that allows folding and winding in a roll to facilitate carrying and has a detachable button key layer.
Nowadays slim size and light weight have become a prevailing trend in the design and development of technology products. However many personal electronic products now available on the market still have the problem of too large size and are not convenient to carry. For instance, the commonly used keyboards such as those used on general computers or notebook computers, usually include an upper casing, a lower casing, a circuit board located between the upper and lower casing, rubber button keys and key tops. After assembly, the keyboards become very bulky and heavy, and are not foldable. Thus they are difficult to carry and use with personal mobile communication products. It becomes a severe constraint on product application scope and area. This also hinders the innovation and development of personal mobile communication products and impairs their economic effectiveness.
Some producers tried to develop portable keyboards that may be folded to multiple sections to facilitate carrying. They usually have a plurality of connection sections defined on a base board mapping against the button keys configuration and intervals. The circuit boards and button keys are made of pliable materials and are mounted on the connection sections. Below the base board, a substrate made of a pliable material is provided. The periphery of the substrate is divided by selected cutting lines and bordered by a jagged and interlocking protection frame. The keyboard thus made may be folded to a smaller size. However it still has a relatively big thickness after folding and is not convenient for people to carry in a bag. Furthermore, when the keyboard is unfolded for use, the bottom and periphery of the keyboard do not have support means at the folding junctures. Hence the keyboard might get loose and moving at the folding junctures when in use, and result in different elevations on different sections. It makes user""s fingers difficult to move around the keyboard during operation. Moreover, the numeral and notation marks embossed on the keyboard tend to wear off after using a period of time.
Then some other producers have developed a soft encasing body to wrap the character and special button keys and circuit board inside to allow the keyboard winding in a roll when not in use. Whereas, those type of keyboards still have the key tops exposed outside the encasing body and result in the wound roll having too large a diameter and make carrying difficult. Furthermore, when using in different countries, the special character button keys have to be changed. It causes inconvenience in production.
The primary object of the invention is to resolve aforesaid disadvantages. The invention provides a membrane keyboard that is foldable and may be wound in a roll to become a compact size to facilitate carrying and has a detachable button key layer to facilitate change and replacement.
Another object of this invention is to provide an interrupt device for stopping signal output from the keyboard so that the keyboard may be used as part of the table top for holding documents and data without the need of moving the keyboard away, and without taking additional useful table top space.
A further object of this invention is to provide durable numeral and notation marks on the button keys that can withstand depressive operation under external force for a long period of time without wearing or loosening off.
To attain the foregoing objects, the membrane keyboard according to the invention includes a bottom layer, a second conductive membrane layer located above the bottom layer that has an output section formed at a selected location of one end linking to an interrupt device, an insulation layer located above the second conductive membrane layer, a first conductive membrane layer located above the insulation layer, a top layer located above the first conductive membrane layer to bond to the bottom layer and having a jutting section to form an opening end, and a button key layer located between the first conductive membrane layer and the top layer.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.